Cool drink dispensers or beverage coolers are known since long time. Inter alia, it is known to provide refrigerators with a water tank, being connected to a water supply pipe, for cooling of the water in the tank and, on command, dispense cool water through a dispenser built-in in the door of the fresh-food compartment. The refrigerator can also be provided with a second tank for adding carbon dioxide to the water to allow dispensing of sparkling water through the dispenser. There are several disadvantages with a cool drink dispenser of this kind. For example, it is bulky, a relatively long time is needed for restoring the cooling temperature of the water after the tank or tanks have been partly or completely emptied and refilled again, and there could be a risk for formation of mould and bacteria in case the dispenser is used only sporadic and the water is stored for long time in the tanks.
To overcome these drawbacks, the present applicant has developed a novel cool drink dispenser, as presented in EP1974802A1. This cool drink dispenser comprises an in-line operating cooling unit connected to a supply source for beverage, typically water. In one embodiment the cooling unit comprises a cooling pipe, through which the beverage flows, and heat accumulating material, such as paraffin or any other similar material surrounding the cooling pipe, absorbs heat from the beverage so as to cool the beverage to a predetermined temperature. To maintain the solid state of the heat accumulating material inside the tubular member, the cooling unit also comprises a cooling circuit, which is located in the heat accumulating material and through which a cooling fluid, such as cold air or any other gaseous or liquid cooling fluid is circulated. The cooling fluid can be cooled inside a freezer compartment of a refrigerator. The cooling circuit can also be formed as an evaporator containing a refrigerant.
In a second embodiment the cooling unit does not comprise the internal cooling pipe. Instead, the cooling unit comprises a tubular body into which the beverage is fed. The tubular body comprises cooling means, which cools the beverage inside the tubular body such that the beverage will freeze to a semisolid, high-viscosity mixture of frozen beverage. By controlling the cooling means in a suitable way, it is possible to limit the percentage of beverage in the solid or semisolid mixture state to not exceed a predetermined maximum ranging between 50% and 90% of the maximum capacity of the tubular body. In this way it is possible to ensure free circulation of beverage inside the tubular body through the solid or semisolid frozen beverage, such that beverage at ambient temperature can mix with and partly melt the solid or semisolid frozen beverage mixture and flow immediately to a dispenser valve where it can be dispensed to a user. In one embodiment the cooling means is formed as a housing surrounding the tubular body and comprises electric fans, which on command can circulate a stream of cold air at a temperature below a freezing temperature for the beverage or a stream of warm air at a temperature above the freezing temperature. The cold air stream can be taken from a freezer compartment of a refrigerator, typically holding a temperature of between −25° C. and 0° C., whereas the warm air stream may be taken from a fresh-food compartment of the refrigerator, typically holding a temperature of between 0° C. and 15° C.
However, a cool drink dispenser according to EP1974802A1 has some disadvantages. In order to prevent completely freezing of the beverage inside and maintain a free passage for the beverage through the cooling unit, it may be necessary to arrange heating elements, which can melt the frozen beverage when necessary. This will result in additional costs for the equipment and the introduction of a device that counteracts with the refrigeration process and thus may lead to increased power consumption. The above described second embodiment also necessitates the arrangement of a dedicated compartment in form of a housing surrounding the tubular body, which results in that the occupied space will increase. It also necessitates a precise sensing system for the formation of frozen beverage but prevent completely freezing of the beverage.
In an additional filed European patent application, EP1906120A1 from the present applicant, is disclosed an alternative appliance for supplying cooled water or other beverage. This appliance comprises an airtight tank for temporarily storing the beverage and the tank is connected to a source, which supplies beverage continuously to the tank. I.e. as soon as cooled beverage is dispensed from the tank, the source supplies fresh, warm beverage to the tank such that it always will be completely filled by beverage. The tank is either made of elastically deformable material or is a rigid container housing a closed capsule made of elastically deformable material and filled with gas. In one embodiment, the tank is accommodated inside a cooling compartment, e.g. formed in a door of a refrigerator. In order to control the temperature of the beverage inside the tank within a desired temperature range, the appliance comprises a number of electric fans which, on command, circulate inside the cooling compartment a stream of cold air, e.g. taken from a freezer compartment inside the refrigerator, or a stream of warm air, e.g. taken from a fresh food compartment in the refrigerator or from outside of the refrigerator. In this way the beverage inside the tank can be maintained at around the freezing temperature. Alternatively, the fans may be replaced by an evaporator inside the cooling compartment. One disadvantage with such an appliance is that the control device for regulating the temperature of the beverage inside the tank will be relatively complicated in order to maintain the temperature as close as possible to the freezing point and yet prevent completely freezing of the beverage and blocking of the tank, which would make it impossible to dispense beverage. Such a regulating including alternate warming and cooling could also lead to increased energy consumption. Another disadvantage associated with such an appliance is that it will require a relatively large space since the tank has to be enclosed by a cooling compartment to allow circulation of warm or cold air around the tank. In another embodiment, the tank is so designed that, even if ice is formed therein, it can expand in a radial direction when there is a sufficient pressure of liquid at its entrance, so as to allow liquid flow. Moreover, the tank may be designed such that some portions of the tank are positioned inside a cooling compartment while others are outside of the cooling compartment.
U.S. Pat. No. 4,866,949 B1 discloses a system for dispensing a chilled, carbonated water or beverage from a conventional home refrigerator. The beverage to be chilled and carbonated is held in a receptacle, the carbonator, having inlet and outlet for the beverage. A coiled evaporator either surrounds or is located inside the receptacle for cooling beverage therein. The beverage level in the receptacle is kept at a predetermined level by a float mechanism extending down in the receptacle leaving a CO2 pocket within the receptacle. A disadvantage with the system described in U.S. Pat. No. 4,866,949 B1 is that it is constructed for dispensing carbonated beverage only and not for dispensing also chilled non-carbonated beverages.